Process for the approximate separation of reaction products resulting from the sulfonation of aromatic bodies.



' No. 889,799. PATENTEDJUNE 2, 1909.

W. MIBRSGH. 4

PROCESS FOR THE APPROXIMATE SEPARATION OF REACTION PRODUCTS I BESULTING'PROM THE SULFONATION OP AROMATIG BODIES.

- APPLICATION FILED PEB- 9, 1907. v SPEOIHBIS.

' discovered that if the reaction WALTI-IER MIERSOH, OF NIEDERS EDLITZ, NEAR DRESDEN, GERMANY.

PROCESS FOR THE APPROXIMATE SEPARATION OF REACTION PRODUCTS RE SULTING FROM THE SULFONATION OF AROMATIG BODIES.

Specification of Letters Patent.

Patented June 2, 1908.

Application filed February 9, 1907. Serial No. 356,631. .(Specimena) To all whom it may concern."

Be it known that I, WALTHER MIERSCH, a subject of the Kinglof Saxony, and residing in Niedersedlitz, near Dresden, Saxony, Germany, haveinvented a new and useful Process for the A proximate Separation of the Reaction Products Resulting from the Sulfonation of 'AromatioBodies, of which the following is a specification.

It'is well known, for the purpose of the further treatment of the reaction products of sulfonating mixtures, to treat, them in aqueous solution with certain alkaliesalts (more particularly common salt, Glauber salt, soda) generally in a cold state, but sometimes by heating the solution (boiling the solution with subsequent cobling). In ad'- dition to these sodium salts, other sodium or potassium salts are also suitable, such, for instance, as sodium sulfite, potassium sulfate, otassium sulfite, potassium carbonate, and c lorid of potassium. The inventor has roducts of the sulfonating mixture be care ully heated with such an alkaline salt the gaseous mineral acid being allowed to escape, if desired, two distinctly separate layers will befinally formed, the upper one of which chiefly consists of or anicsubstances, that is to say the sulfonate orrned, together with residues of the .sulfonating mixture. that remain unchanged, and the bottom-heavier layer almost entirely of bisulfate.

In carrying out the process with common salt, for example, the reaction products of the sulfonating mixture 'arefirst heated to about 40 C. and then thesa'lt isadded in small consecutive ortions, or continuously, in such manner t at there should be a continuous generation .of gas, but no overboiling, the gas being allowed to escape if desired.- The temperature is gradually increased as the salt introduced later'on-takes part in the reaction with greater difficult The heating is continued until the salt lies all beenintroduced and practically used up by which time the temperature should be from 130 to 140 C. At this point the formation of two separate layers has commenced, and to complete the formation the temperature is in creased, if necessary, to about 170180 C. The upper layer consists'chiefly of organic substances, that is to say, of the sulfonate :mixture in reaction contains su for carrying on the work with a satisfactory formed, together with residues of the mixture that remain unchanged, the bottom layer consisting almost entirely of bisulfate. This affords a new Way of separating in a simple and rational manner the organic roduct (su'lfonate and sulfonic 'acid) from t e inorganic ingredients of the mixture, abisulfate I being obtained as a marketable product. The

upper layerstill contains, it is true, some inorganic substances, but, owing to their small proportion, it can be further treated in a ver simple and convenient manner. Inthe investigations which led to this mve'ntion, the starting point was not the usual reaction product of a sulfonating mixture more or less diluted with water; on the con-- trary the work of sulfonation was carried on without any addition of water, so that there could only be the question of working in a molten state, but 'not of working with an aqueous solution, As in that way 1t was possible to bring about the formation .of layers without evaporating useless quantities of water, and as, moreover, the volume to be handled was considerablysmaller, an addition of water in carrying out the process according to this invention must be avoided as much as possible. Generally s eaking, the cient water output of sulfonate' of sodium. If,.in the example given. 12 kgs. of common salt are usedfor 58 kgs. of the reaction product of'su'lfonation, there is no necessity to add any water. Even if 14 kgs. of commonsalt are used, the

object can be attained provided the work is carried on in a careful manner. In the latter case it is, however, advisable to add, as an additional precaution, a little water, namely, about 10% of the reaction mixture. dition ofwater is therefore made in cases in which, for the purpose of increasing as far as possible, the output of sultonate of sodium,

An ad- I it is desired to use as large aquantity of common salt as possible. This addition of water is effected beforehand. But even in such cases for economic reasons, the addition should not exceed the amount required for that pur ose.

It is obvious that the process in question can be a plied only to such sulfonic acids as are not ecomposed at the temperatures and under-the other conditions required for carrying out the process. Another requirement for the possibility of applying this process, is the presence of a sufficlent excess of sulfurlc acid in the sulfonating mixture which, however, exists in most cases.

In treating a reaction product containing benzol-mono-sulfonic. acid,- an artificial addition of sulfuric acid need not be made, as the product in itself contains sufficient sulfuric acid for bringing about the reactions desired. There may, however, be cases which the process in question is not appl1 cable (although the sulfonic acids in question are otherwise quite suitable for the purpose) only because the reaction mixture does not contain sufficient sulfuric acid required by the reactions intended in which cases therefore it would be necessary to use artificial addition of sulfuric acid.

A reaction product as shown in the follow ing table has been successfully treated:

' U 0 and I 1 CH traces ol Benzol. H280 6 i iiiplalign -logether.

stances.

1. Reaetionprodnot with 100% sulfuric acid 5 produced 2.00 32.09 50.00 8.41 100.0 1

As an example, a method of carrying out the process with a mixture containing benzene-mono-sulfonic acid by the addition of common salt may be described 58 kgs. of the last mentioned mixturewith about 10 "a of free water are gradually mixed with about 12 kgs. of common salt and carefully heated. Gaseous hydrochloric acid will then escape. At BO-140 (1., sometimes (for reasons which cannot be easily explained) only at a slightly highertemperature, the above mentioned formation. of layers takes place. The development of hydrochloric acid is then nearly completed, and the layers can be sharply separated with very little trouble. The upper layer contains, in addition to free benzene-sulfonic acid and a little free sulfuric acid, completed sul'fonate of sodium, the bottom layer consists only of a marketable bisulfate of sodium, approximately of 9095 of pure bisulfate. It should be remarked that it is not here a question of the mere settling of the bisulfate separated in a solid when cold solidifies.

state. In that case it would be impossible to talk of two layers. If it were so, in view of the temperature employed there would be a single liquid with a solid settlement or precipitate at the bottom. The bottom (or bisulfate) layer appears, however, as a fairly clear layer which, when hot, is liquid and which solidifies only on cooling, and the upper -(sulfonic) .layer is dark when hot, and

After cooling, the bi I sulfate layer is non-transparent, of a white to dirty-white color, brilliant, and of course crystalline structure, while the fine crystal' line sulfonic layer is lighter in weight and by arranging in a vessel with a conical bc'rtom two super osed cocks in the well known manner, and a owing first the bisulfate layer to escape through the bottom one, and then the sulfonic layer through'the upper one, as

soon as dark hquid appears when the upper cock is opened. It is also possible to se arate the two cakes in solid state by forcing them apart. o

The process could be carried out in a rational manner in an apparatus shown in the accompanying drawing in which A is the boiler with arched cover B which is built'into a suitable furnace C with combustion chamber D. The bottom a of the boiler is inclined towards one side. At the lowest outlet with a cock 0, and at the 'ghest point of the bottom the outlet d with a cock e. After the treatment of a charge, the line 0 0 may indicate the level of the upper layer,

and the line a u the level of the bottom layer.

Then, by opening the cock 0, the bottom layer is drawn oil.- As soon as, on opening the cock 0, nothing )f the bottom layer is seen, the cock 0 is closed, and the upper layer discharged through the cock e. In this way, the chief quantities of the two layers can be neatly separated. The mass fromthe contact zone between the two layers remains oint of the bottom is arra ed the then as a residue in the boilerA and is added to the new charge.

From an opening 1n the cover b of the boiler, starts a pipe E which either conveys the gaseous mineral acid (if it is not to be recovered) into a chimney, or, if it is desired to obtain theacid as a byproduct, more particularly hydrochloric acld, into a condenser not shown in the drawing; The funnel F wilth a valve can be used for introducing the sa t.

What I claim as my invention and desire to secure by Letters Pate is 1. The herein desorib. (1' process for obtaining a mixturecontaining aromatic sulfonic acids and their s"lts of alkali metals which consists in mixithe reaction product of sulfonation with an lkali salt of a mineral acid and cautiously heating the mixture until it separates into two layers containing respectively the bisulfat'eof the alkali and the sulfo-compounds.

2. The herein described process for obtaining a mixture containing aromatic sulfonie acids and their salts of alkali metals which consists in mixing an undiluted reac tion product of sulfonation with an alkali salt of a mineral :acid and cautiously heating the mixture until t separates into two layers containing respectively the bisulfate of the alkali and the sulfo-compounds.

3; The herein described process for obtaining a mixture containing aromatic sul- 5 fonic acids and their salts of alkali metals which consists in mixing a reaction product of sulfonation with an a kali salt suitable for fixing the acids formed, and cautiously heating the mixture until it se arates into two i 10 layers containing respective y the bisulfate of" the alkali and the sulfo-compoundS.

4. The herein described process for obtaining a mixture containing aromatic sulfonic acids and their salts of alkali metals 15 from the reaction products of sulfonation containing sulfuric acid, which consists in mixing with the said products a salt of an alkali which will fix the acids produced and cautiously heating the mixture untilit separates into two layers containing respectively the bisulfate of the alkali and the sulfo-compounds. y

In testimony whereof I havesigned my name to this specification in the presence of two subscribing witnesses.

WALTHER MIERSCH; Witnesses:

PAUL LIENEMANN,

RIcHARD IFFERTE. 

